I could be wrong, but I always understood that turbos work better with dense air, hence better gain with an intercooler (dense air); sea-level (dense air). Natural displacement is the way to go up high. Anyone feel free to make a factual rebuttal.

Ivan(Cincinnati):
01 Nemo 4.2 (me);
99 A4q 2.8(daughter);
98 A6q Wagon(wifey)Pearl-Ecru,boughtnew!
96 A4q 2.8 pearl (son);
67 TR4A-IRS in hot-rod restoration.
Do my own work; Vag-Com;
Gone but not forgotten: 98 A6q;98 A4q 2.8; 93 100cs;66 Ejag,TR3A,TR4,TR6, MGB,MGB-GT,MG Midget; 280Z;
57 Chevy 327 (self-installed);62 Chevy; 64 Valiant Wagon slant-6 (the original A6 C4 wagon design); Corvairs(a gaggle);various Honda bikes, etc (since 1970).